The coast guard sent patrol boats and helicopters to search for the crew. Five bodies were found inside the capsized boat late in the afternoon and their hearts were no longer beating, said Koji Takarabe, another coast guard spokesman.

The Jia Hui's 12 Chinese and one Malay crew were unharmed, and were being questioned aboard the ship about what had happened. It was still unclear what caused the collision, Takarabe said.

The 498-ton Eifuku Maru was traveling from Nagoya, central Japan, to Ichikawa, east of Tokyo. The 2,962-ton Jia Hui was headed from Kawasaki, Japan, to Busan, South Korea.